1. Field of the Invention
The present invention relates to a method and an arrangement for determining inertial position angles of a vehicle from measured accelerations and to a method and arrangement for determining rotation angles of the vehicle from the inertial position angles and measured rotation rates.
2. Prior Art
In German Patent Application 196 09 717.1, which was not published by the filing date of the present application, an arrangement for detecting rollover events in vehicles is described. If a vehicle turns over, protection devices installed in the vehicle must be tripped in time; these include for instance roller bars, belt tighteners, and various air bags. If all these protective devices are to be tripped in time, a detection must be made as early as possible whether rotations of the vehicle about its vertical axis, longitudinal axis and transverse axis will cause it to overturn. Mistakes in deciding about a rollover event must be precluded as much as possible so that the restraint devices will not be tripped for instance if the vehicle is parked on a steep slope or is experiencing slow rotational events on cornering. To prevent mistaken decisions in sensing rollover, the inertial position, that is, the outset position of the vehicle relative to the ground-based coordinate system, must be known. The rollover sensing must detect whether rotary motions of the vehicle out of this inertial position are so great that the vehicle will overturn. To prevent mistakes in rollover sensing, it is therefore important to determine the inertial position of the vehicle as exactly as possible. Slow dynamic vehicle motions, such as running up onto a berm, taking a sharp corner, and braking or acceleration events should therefore not affect the ascertainment of the inertial positional angle of the vehicle.